Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
914 PM EST Sat Feb 13 2016
trough of low pressure will gradually shift off to the southeast
tonight as Arctic high pressure builds in from the west. High
pressure will continue to build in from the west Sunday and crest
over the area Sunday night. High pressure will shift offshore on
Monday as a warm front approaches from the southwest. Developing
low pressure moving up the East Coast will push the warm front
north of the region on Tuesday. Low pressure will lift north into
Canada Tuesday night and a trailing cold front will swing through
the region. High pressure will build and then crest over the
region Thursday and Thursday night moving offshore Friday as a
warm front approaches from the west.
Near term /until 6 am Sunday morning/...
915 PM update...have updated the forecast to cancel the Winter
Storm Warning and winter weather advisories for the middle coast as
only occasional light snow or flurries remain. This should move
out over the next few hours. In addition...have lowered overnight
temperatures a few degrees based on latest trends in observational
data. The temperatures sure plummetted fast this evening. The
result is an expansion of the wind chill warning to the coast.
615 PM update...inverted trough affecting the middle coast of Maine
continues to weaken and pull away this evening. However...warnings
and advisories for snow will remain in effect this evening since a
few bands continue to develop overhead from time to time.
Otherwise...temperatures dropping like a rock with very cold wind
chill values continuing.
Surface cold front has just about cleared the County Warning Area...its getting a
little hung up as it encounters the inverted trough near
Penobscot Bay. Any shsn should be done except in the vicinity of
the inverted trough. The trough has weakened still think the
trough may flare a bit after this interaction...but still think it
will remain intact...and could flare up a little through early
evening...but the bulk of the now has already fallen from this
system. Did drop the advisory for Lincoln County as the latest
models have stopped the shift westward of any significant
snow...so...any addl accums in eastern Lincoln City will be light. The
snow will gradually lighten in Knox and Waldo counties...and
should end around midnight or shortly before.
As for the rest of the County Warning Area...the cold air advection has begun in full force with
northern and far western zones already approaching zero as temperatures fall and
we experience a very cold night. All wind chill products remain as
is with wind chills approaching -40 in the north and reaching -25
along the coast. Air temperatures will range from about -15 in the north to
zero to 10 below in the south. Can't rule out a few upslope shsn
of flurries in the mountains....but they will be moisture starved as
the very dry air moves in.
Short term /6 am Sunday morning through Sunday night/...
after a bitter cold morning...will see temperatures climb a little...but
with very cold air overhead and surface cold air advection continuing through at least
part of the day...highs will be quite limited ranging from near 10
on the coast and in southern New Hampshire...to zero to five below in the north.
The good news is that despite all this cold it will be sunny.
Should get of advection level wind chills in the coastal plain and
eventually, the foothills by afternoon...as winds begin to
diminish...but will likely have to convert the wind chill warning
in the north to advisories for Sunday into Sunday evening.
The surface high builds in late sun and moves into New England Sun
night. This will allow winds to die off after sunset and also
allow many locations to decouple. This could lead to some very low
temperatures in the sheltered mountain valleys...where rad cooling could
bring temperatures close to -30 in a few spots. Otherwise look for lows
Monday morning similar to Sunday morning...but without the wind.
Long term /Monday through Saturday/...
very active pattern shaping up for the week...
Arctic high pressure moves off the coast Monday allowing a return
warm air advection southerly flow to develop in the afternoon. By Monday night snow
will develop from southwest-northeast across the area as the warm air advection
barolclinic zone begins to tighten and increases forcing. By late
Monday night steady accumulating snow should be widespread with
several inches accumulation by Tuesday morning across all areas. Over
southern areas the precipitation Tuesday morning will quickly change
to a mix and then rain while further north in the mountains
significant accumulations of snow may occur before any changeover
occurs. For accumulations used snow ratios based on temperatures on a
cross section. Considering amount of initial quantitative precipitation forecast and Arctic air
in place before the changeover...fairly high confidence of
plowable snow even across southern areas. All models show a very
strong surge of warm air advection but considering depth and strength of Arctic
air mass had to lower temperatures some Tuesday especially in the mountains.
In low levels cold air will be hard to scour out Tuesday morning over
southern areas so a period of freezing rain may occur before
afternoon temperatures finally surge well above freezing and changes
ptype to all rain. The system quickly exits by Tuesday night followed
by a cold front and scattered snow showers. A return to colder
temperatures Wednesday out ahead of another digging trough. This may pose a minor
problem for Thursday with very limited moisture so expecting only
scattered snow showers with the system. Some accumulations may
occur in the mountains. High pressure builds in for Friday but a Canadian
clipper system will be on its heels by late Friday spreading a period
of snow or mixed precipitation across the area by Sat.
Overall stayed close to superblend output with exceptions Monday
night into Tuesday as described above.
Aviation /02z Sunday through Thursday/...
short term...gusty northwest winds...as high as 25kt or so will continue
through the evening before diminish a bit after midnight. Krkd
will see occasional IFR in snow through early this evening...and should
settle at VFR after midnight. Otherwise....expect VFR through Sun
Long term...VFR through Monday. Could see extended period of IFR or
lower in snow/fzra/ra Monday night into Tuesday night. Winds may become
short term...gales and very cold air will combine to produce heavy
freezing spray overnight into Sun morning...with some Arctic sea
smoke possible. Winds will begin to slacken Sun morning...but
will likely see Small Craft Advisory winds into sun evening. While freezing spray
will become less intense during Sunday...will probably need an
advisory into Sunday evening.
Long term...winds and waves will increase Monday night. Gale force
winds and high seas are possible by late Tuesday. Tuesday night winds will
quickly diminish and seas will gradually subside Tuesday night.
Northwest winds Wednesday but below Small Craft Advisory criteria. By Thursday northwest
winds may increase and reach Small Craft Advisory criteria as Arctic high pressure
builds across the waters.
ME...wind chill warning until 10 am EST Sunday for mez012>014-
Wind chill warning until 10 am EST Sunday for mez007>009.
New Hampshire...wind chill warning until 10 am EST Sunday for nhz004>015.
Wind chill warning until 10 am EST Sunday for nhz001>003.
Marine...heavy freezing spray warning until noon EST Sunday for
Small Craft Advisory until noon EST Sunday for anz151-153.
Gale Warning until noon EST Sunday for anz150-152-154.
Near term update...ekster